Chinese astronauts conducted a science lecture 400 kilometers above Earth to millions of students on Thursday afternoon, as they orbited in the Tiangong space station.

Major General Zhai Zhigang, Senior Colonel Wang Yaping and Senior Colonel Ye Guangfu, all members of the Shenzhou XIII mission crew, greeted students, teachers and other participants when the lecture started at 3:54 pm. They showed viewers how they live and work inside the space station, which currently consists of a core module, a spacecraft and two robotic cargo spaceships.

The astronauts displayed their exercise equipment and a specially designed space suit, and conducted demonstrations on physical phenomena in microgravity, such as "disappearing buoyancy" and a "water ball". Ye, who is on his first spaceflight, showed how he rotated his body in the weightless environment. The astronauts also answered questions from students during the lecture.

Tens of millions of primary and middle school students across China watched the hourlong televised event hosted by the China Manned Space Agency, the Ministry of Education and other government departments.

A total of 1,420 invited students in Beijing; Nanning, capital of the Guangxi Zhuang autonomous region; Wenchuan, Sichuan province; and the Hong Kong and Macao special administrative regions were present at "ground class venues", with some taking part in video chats with the crew members during the lecture.

It was the first lecture of the Tiangong Class, or Heavenly Palace Class, China's first extraterrestrial lecture series to popularize space science.

More lectures will be held based on the country's manned spaceflights and will also be presented by Chinese astronauts, the manned space agency said. Such activities are intended to spread knowledge about manned spaceflights and spark enthusiasm for science among young people, it added.